You are right,there is no absolute guarantee,but something is better than nothing.If nothing else ,maybe the potential thief will realise that I'm serious about protecting my rights and will be discouraged(wishful thinking,I know !).
Hi Anindya, it is really unfortunate that there are people who use other peoples images without permission, but it is rather diffucult to stop them. In this case, it will only take them a minute to make the image usable. (I am attaching a low-res version here).
Anyway, in the present situation it turns out to be a compromise between preserving the beauty of the image, and its safety.
Thanks Suvro.I'm still sorting out the Puri pix;I'll try out monochrome after I finish basic PP. Recently photo theft by newspapers and even ad agencies is on the rise(Subrotoda has been hit thrice,i.e,thrice he knows of)so I thought a little bit of safeguard by watermarks is warranted.